This invention is directed to a suction device for a bale opener, for sucking off fiber flocks, having a suction hood being arranged above the opening means of the bale opener, extending over the whole bale-reducing width and being connected with a suction channel for removal of the sucked fibers, which suction hood has a suction opening facing the bale surface and consists of two opposite side walls and a rear hood-limiting wall delimiting the suction hood on the side of the opening means facing the suction channel and an upper hood-limiting wall delimiting the suction hood toward the top and extending from the suction channel to the side of the opening means facing away from the suction channel.
By such suction devices, the fibers, having been detached from a bale by a bale opener, are sucked off and carried into a transport air stream.
German Laid-open 36 02 898 discloses a suction device arranged at a bale opener for fiber bales, e.g. cotton bales or bales of chemical fibers, in which suction device at least one opening roller is arranged in a housing, the detached fiber flocks being removed in the direction of the longitudinal axis of the opening roller by a suction air stream prevailing within the housing. The suction device, in addition to its two side walls, is provided with two inclined faces for air discharge, rising laterally to these side walls. One of said inclined faces projects in a nose-like manner, into the sucking section and thus, in the lower region of said section, forms an almost symmetrical suction funnel above the bale reducing area.
Such an arrangement of the sucking section above the bale reducing area is disadvantageous in that the sucking section is substantially reduced already slightly above the bale reducing surface whereby an increased suction capacity is required for a certain flow volume. A further disadvantage consists in that the air streams, emerging out of the region below the nose projecting into the sucking section, first flow in a direction almost opposite to the transport air stream and then, at the front end of the nose, have to be deflected by about 140.degree.. This strong deflection of a considerable portion of the overall air stream results to further energy losses, leading also to increased air consumption.
It is the object of the invention to improve a suction device of the above type in such a manner that the specific air and energy consumption is reduced.
According to the invention, this object is solved in that the highest point of the upper hood-limiting wall is arranged in the central area of the bale-reducing width and in that the rear and the upper hood-limiting walls of the suction hood are provided with a continuous curve.